Solution and method for scavenging sulphur compounds

ABSTRACT

There is disclosed herein a solution for removing a sulphur compound or carbon dioxide from a fluid and methods for its use, said solution comprising sulphuric acid, a metal at between about 0.05 to 10 percent by weight, an amine at between about 10 to 80 percent by volume and water. In one aspect, the sulphuric acid is in the form of a chelating agent and in another it is in the form of a derivative of a sulphur-based acidic compound. The sulphur compound may be hydrogen sulphide, carbonyl sulphide or a mercaptan. In one aspect, the method is practiced at temperatures significantly below zero. In another aspect, this invention is an acid/amine solution comprising sulphuric acid, sulphuric acid in the form of a chelating agent, or a derivative of a sulphur-based acidic compound and monoethanolamine. This solution may be used as a source of monoethanolamine.

FIELD OF THE INVENTION

This invention relates to a solution that can be used in removinghydrogen sulphide, mercaptans, carbonyl sulphide and carbon dioxide fromgases and liquids.

BACKGROUND OF THE INVENTION

Hydrogen sulphide is a colorless gas, with an odor of rotten eggs. It isproduced by bacterial action during the decay of both plant and animalprotein and can be formed wherever elemental sulphur or certainsulphur-containing compounds come into contact with organic materials athigh temperatures. In industry, it is usually an unintended byproduct,for example from the production of coke from sulphur-containing coal,from the refining of sulphur-containing crude oils, the production ofdisulphide, the manufacture of vicos rayon, and in the Kraft process forwood pulp.

Natural gases with high concentrations of hydrogen sulphide are known as“sour gases”. Hydrogen sulphide in sour gas and crude oil streams isseparated during the “sweetening” process. The most widely usedsweetening processes in the industry are the amine processes, which usea solution of water and a chemical amine to remove carbon dioxide andseveral sulphur compounds.

Hydrogen sulphide is also a byproduct of wastewater from treatmentplants or water from agricultural practices. Additionally, hydrogensulphide can be responsible for the unpleasant odor from liquids used injanitorial processes, RV holding tanks, portable toilets and the like.If the emission of hydrogen sulphide from these liquids can becontrolled, then the unpleasant odors may be eliminated.

Hydrogen sulphide is toxic to humans and other animals, and represents asignificant threat to public safety and health. It can cause seroushealth risks, most notably in the oil and gas, livestock, wastemanagement and janitorial industries. At 200 parts per million, humanscan no longer smell the gas, and therefore can no longer detect it bysmell. Higher concentrations than this can cause nausea and headaches.At 500 to 1,000 parts per million, it causes unconsciousness, with deathfollowing in two to twenty minutes unless the victim is removed from thearea of exposure immediately.

There is a need for a simple, economical and effective means ofcapturing hydrogen sulphide gas that is present in other gases, or inliquids.

SUMMARY OF THE INVENTION

This invention provides a solution that can be used to remove hydrogensulphide from gases and liquids, and methods for its use. The solutionand methods of this invention can also be used to remove, from gases andliquids, other sulphur compounds, such as carbonyl sulphide, mercaptans,including methyl mercaptan, ethyl mercaptan, n-propyl mercaptan and/oriso-butyl mercaptan. Additionally, the solution and methods of thisinvention can be used to remove carbon dioxide from gases and liquids,particularly in cold temperatures.

Accordingly, in one aspect the invention is a solution for removing asulphur compound or carbon dioxide from a gas or a liquid, said solutioncomprising:

-   (a) sulphuric acid, at between about 0.1 to 10 percent by volume of    the solution;-   (b) a metal, at between about 0.05 to 10 percent by weight of the    solution;-   (c) an amine at between about 10 to 80 percent by volume of the    solution; and-   (d) water.

In one embodiment the sulphuric acid is in the form of a chelatingagent. In one embodiment, the sulphuric acid is present at between about0.1 to 2 percent by volume of the solution. In one embodiment, the metalis between about 1 to 5 percent by weight of the solution.

In another aspect, the invention is a solution for removing a sulphurcompound or carbon dioxide from a gas or a liquid, said solutioncomprising:

-   (a) a metal/acid mixture at between about 25 to 75 percent by volume    of the solution, said metal/acid mixture comprising:    -   (i) sulphuric acid in the form of a chelating agent, at about 2        percent by volume,    -   (ii) a metal, at between about 1 to 10 percent by weight, and    -   (iii) water; and-   (b) an amine at between about 10 to 80 percent by volume of the    solution, and-   (c) water.

In one embodiment, the metal/acid mixture is present at between about 25to 50 percent by volume of the solution. In one embodiment the metal ispresent at between about 1 to 5 percent by weight of the solution.

In another aspect, this invention is a solution for removing a sulphurcompound or carbon dioxide from a gas or a liquid:

-   (a) a derivative of a sulphur-based acidic compound at between about    0.5 to 10 percent by volume of the solution,-   (b) a metal, at between about 1 to 10 percent by weight of the    solution,-   (c) an amine at between about 10 to 80 percent by volume, and-   (d) water.

In one embodiment, the derivative of a sulphur-based acidic compound ispresent at between about 1.25 to 3.75 percent by volume of the solution.In one embodiment the metal is present at between about 1 to 5 percentby weight of the solution.

In the above aspects the sulphur compound may be hydrogen sulphide,methyl mercaptan, ethyl mercaptan, n-propyl mercaptan, iso-butylmercaptan and/or carbonyl sulphide. In various embodiments of the aboveaspects, the metal is copper, zinc, or a mixture of copper and zinc. Inother embodiments the metal is selected from the group comprising iron,manganese or magnesium, or a mixture thereof. In various embodiments ofthe above aspects, the amine is monoethanolamine, diglycolamine,methyldiethanolamine, or a mixture of amines. In one embodiment, theamine is present at between about 25 to 50 percent by volume of thesolution.

In another aspect, this invention is a solution for removing a sulphurcompound from a fluid, said solution comprising:

-   (a) a derivative of a sulphur-based acidic compound at between about    1.25 to 3.75 percent by volume of the solution-   (b) a metal, at between about 1 to 5 percent by weight of the    solution,-   (c) monoethanolamine at between about 25 to 50 percent by volume of    the solution, and-   (d) water.

The sulphur compound may be hydrogen sulphide, methyl mercaptan, ethylmercaptan, n-propyl mercaptan, iso-butyl mercaptan and/or carbonylsulphide. In one embodiment, the derivative of a sulphur-based acidiccompound is at about 2.5 percent by volume of the solution. In oneembodiment, the metal is at about 2 to 4 percent by weight. In another,the metal is either copper or zinc. The monoethanolamine may be presentat about 25 or 50 percent by volume of the solution.

In another aspect, this invention is a method of removing sulphurcompound or carbon dioxidefrom a fluid, which method comprises:

-   (a) preparing a solution according to one aspect of this invention,    and-   (b) contacting the fluid with the solution.

The sulphur compound may be hydrogen sulphide, methyl mercaptan, ethylmercaptan, n-propyl mercaptan, iso-butyl mercaptan and/or carbonylsulphide. The fluid may be a gas, such as natural gas, or air.Alternatively, the fluid may be a liquid, such as a liquid hydrocarbonor drilling mud. In one embodiment, this method is practiced at atemperature of between about ° C. and −51° C., and in another at atemperature of between about −10° C. and −40° C.

In another aspect, this invention is a method of removing a sulphurcompound or carbon dioxide from a gas, which method comprises:

-   (a) preparing a solution according to the invention, and-   (b) contacting the gas with the solution,    and which is characterized in that it is performed at a temperature    of between about 0° C. and −51° C., or between about −10° C. and    −40° C., −20° C. and −40° C. or −10° C. and −30° C.

In another aspect, this invention is an acid/amine solution comprising:

-   (a) sulphuric acid, at between about 0.1 to 10 percent by volume of    the solution;-   (b) monoethanolamine, at between about 10 to 80 percent by volume of    the solution; and-   (c) water.

In one embodiment, the sulphuric acid is in the form of a chelatingagent. In one embodiment, the sulphuric acid is present at between about0.1 to 2 percent by volume of the solution.

In another aspect, this invention is an acid/amine solution comprising:

-   (a) a derivative of a sulphur-based acidic compound at between about    0.25 and 10 percent by volume of the solution, and-   (b) monoethanolamine at between about 10 to 80 percent by volume of    the solution, and-   (c) water.

In one embodiment, the derivative of a sulphur-based acidic compoundcomprises between about 1.25 and 7.5 percent by volume of the solution.In another embodiment, the monoethanolamine comprises between about 25to 50 percent by volume of the solution.

In yet another aspect, this invention is a solution comprising theacid/amine solution disclosed herein, wherein the acid/amine solution isused as a source of monoethanolamine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a drawing of an apparatus used in the method of thisinvention.

FIG. 1B is a drawing of another apparatus used in the method of thisinvention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

There is disclosed herein a solution that can be used to remove hydrogensulphide and other sulphur compounds from gases and liquids, or in anysituation where hydrogen sulphide is generated. Particularly, it may beused to remove hydrogen sulphide from natural gas collected from oil andgas wells. “Sulphur compound” as used herein includes hydrogen sulphide,methyl mercaptan, ethyl mercaptan, n-propyl mercaptan, iso-butylmercaptan and carbonyl sulphide.

The solution of this invention is a mixture of an acid, a metal, anamine and water.

The acid component of the solution is sulphuric acid. Variousembodiments of the solution of this invention include sulphuric acid atabout 0.5, 0.6 or 1, 2, 3, 4 or 5 percent by volume of the final volumeof the solution. In another embodiment, the range of sulphuric acid isbetween about 0.1 to 2 percent by volume of the final volume of thesolution. In yet another embodiment, the range of sulphuric acid isbetween about 0.1 to 10 percent by volume of the final volume of thesolution. When referring to a percentage by volume of sulphuric acidherein, reference is made to a concentrated solution of sulphuric acidthat is about 98% sulphuric acid, or about 18 molar sulphuric acid, ascan be obtained, for example, from Fisher Scientific.

In one embodiment, the sulphuric acid is in the form of a chelatingagent, such as is available from Cheltec, Inc. (U.S.A.), as a productcalled Stabitrol™. This derivative has the added benefit of having avery low level of corrosiveness to human or animal tissue, while stillbeing a strong acid. Chelate, as used herein means the process thattraps and binds certain metal ions to hold them in suspension inliquids. Metal ions that are suspended in liquid will not dissolve asquickly and will bind with bacteria or other metal ions. The feature ofchelation is useful because it improves odour control, increases theeffectiveness and performance of products such as herbicides andpesticides and permits precious metal extraction without the need forcaustic chemicals. “Chelating agent” as used herein refers to a moleculethat can chelate metal ions.

One embodiment of the -solution of this invention includes sulphuricacid that is in the form of a chelating agent at a range between about0.1 to 10 percent by volume of the final volume of the solution. Inanother embodiment, the range of sulphuric acid in the form of achelating agent is between about 0.1 to 2.0 percent by volume of thefinal volume of the solution. In specific embodiments, sulphuric acid inthe form of a chelating agent is present at about 0.5, 0.6, 1, 2, 3, 4or 5 percent by volume of the final volume of the solution. An about 2percent solution of sulphuric acid in the form of a chelating agentreferred to herein, is an about 10-fold dilution of Stabitrol™ or asolution of a substantially chemically equivalent compound.

In another embodiment, the sulphuric acid is a derivative of asulphur-based acidic compound, such as is available from Cheltec, Inc.(U.S.A.), as a product called Stabitrol™ which is indicated by Cheltecto be a 50 percent derivative of a sulphur-based acidic compound. Anabout 5 percent by volume solution of a derivative of a sulphur-basedacidic compound referred to herein, is a solution of about 10 percent byvolume Stabitrol™, or a solution of a substantially chemicallyequivalent compound. An about 5 percent by volume solution of aderivative of a sulphur-based acidic compound provides a sulphuric acidthat is useful in the solution of this invention. In one embodiment, therange of the about 5 percent solution that is used is between about 10to 75 percent by volume of the solution of this invention, and inanother embodiment, between about 25 to 75 percent by volume of thesolution. In yet another embodiment, the range of the 5 percent solutionthat is used is between about 25 to 50 percent by volume of the solutionof this invention. In yet another embodiment, the solution comprises upto 10 percent by volume of the derivative of a sulphur-based acidiccompound.

The metal component of the solution comprises between about 0.05 to 10percent by weight of the solution, and exists as a metal ion insolution. In preferred embodiments, the metal component is copper orzinc, however it may be iron, magnesium or manganese. In yet anotherembodiment, it may be a mixture of any of the above metals. The iron inthe solution may be derived from mixing solid iron sulphate with wateror another liquid.

In one embodiment the amount of copper in the solution is between about1 to 99 percent by volume of an about 5 percent by weight solution ofcopper. In yet another embodiment, the amount of copper in the solutionof this invention is between about 25 to 75 percent by volume of anabout 5 percent by weight solution of copper. In yet another embodiment,the amount of copper in the solution of this invention is between about25 to 50 percent by volume of an about 5 percent by weight solution ofcopper. The copper solution may be derived from mixing solid coppersulphate pentahydrate with water or another liquid. Solid coppersulphate pentahydrate useable in the methods of this invention may beobtained, for example, from HCI Canada Inc., in the form of a solid thatis 25.2 percent copper.

In another embodiment the amount of zinc in the solution of thisinvention is between about 1 to 99 percent by volume of an about 6 to 9percent by weight solution of zinc. In yet another embodiment, theamount of zinc in the solution of this invention is between about 25 to75 percent by volume of an about 6 to 9 percent by weight solution ofzinc. In yet another embodiment, the amount of zinc in the solution ofthis invention is between about 25 to 50 percent by volume of an about 6to 9 percent by weight solution of zinc. The zinc solution may bederived from mixing solid zinc sulphate monohydrate with water oranother liquid. Solid zinc sulphate monohydrate useable in the methodsof this invention may be obtained, for example, from TetraMicronutrients, in the form of a solid that is 35.5 to 38 percent zinc.

The amine component of the solution is added as a substantially pureliquid of the amine, or solution of mixed amines. Amines are acolourless, viscous, flammable liquid with a fishy, ammonia-like odor,and they are miscible in water, acetone and methanol. One embodiment ofthe solution comprises amines in the range of between about 10 to 80percent by volume of the solution. In another embodiment the solutioncomprises amines in the range of between about 25 to 75 percent byvolume of the solution. On yet another embodiment the solution comprisesamines at between about 25 to 50 percent by volume of the solution.

In one embodiment the amine is monoethanolamine, otherwise known asethanolamine. In other embodiments of the solution other amines, such asdiglycolamine (DGA) and methyldiethanolamine (MDEA) or a mixture amines,may be used. The inventors have shown that if the monoethanolaminecomponent of the solution comprises about 2 percent by volume of thefinal volume of the solution, the solution is stable, meaning that themetal component remains in solution. However, the solution does not workas well at scavenging hydrogen sulphide as when the monoethanolaminecomponent is present at a higher percentage. If the monoethanolaminecomponent of the solution comprises between about 2 and 10 percent byvolume of the final volume of the solution, the inventors have shownthat solution becomes unstable, in that the metal component willprecipitate out of solution. At above 10 percent by volume ofmonoethanolamine, the solution is once again stable.

The last component of the solution of this invention is water, which maybe used to bring the volume of the solution to its desired final volume,or which may already be provided by other components of the solution.One embodiment comprises water at a final volume percentage of betweenabout 20 to 80 percent of the final volume of the solution. Anotherembodiment comprises water at 25 to 75 percent of the final volume ofthe solution.

The inventors have shown that various embodiments of the solution ofthis invention do not freeze at even as low as −51° C. The results ofthe freezing point analysis are described more fully in Examples 1 and 6contained herein. The solution can, therefore, be used to removehydrogen sulphide and other sulphur compounds and other contaminants, invery cold environments. It is noted that the removal of carbon dioxideby this solution appears to be more efficient at cold temperatures thanat warmer temperatures, as shown by Example 5. The significantdepression of the freezing point was an unexpected result, however itprovides the benefit of being able to use this solution at temperatureswhich would cause other solutions, and in particular other solutionsthat can be used to scavenge hydrogen sulphide, to freeze. Aparticularly beneficial use of this solution is in truck scrubbers, asthey are used in the field, and may be used at temperaturessignificantly below freezing. The fact that this solution does notfreeze at very low temperatures provides the additional benefit thatstorage of the solution is simplified, as the potential for the solutionto freeze during storage is not a concern. With a freezing point ofbelow −51° C., it is likely that the solution could be used to removesulphur compounds and carbon dioxide from gases that are at thistemperature.

The inventors have also shown in Example 1 disclosed herein, that asolution of 50 percent monoethanolamine: 50 percent of a solution ofabout 2 percent (v/v) sulphuric acid in the form of a chelating agent (5percent (v/v) Stabitrol™), will not freeze even as low as −51° C.Example 6 extends these results to show that solutions of 2.5, 10 or 15percent (v/v) Stabitrol™ and 50 percent (v/v) motoethanolamine, do notfreeze even at −48° C. Therefore, this solution may be useful inproviding monoethanolamine in a form that can be used at temperaturesthat would cause monoethanolamine or other monoethanolamine solutions,to freeze. One potential use of this monoethanolamine is in a paintstripper that will be used in cold temperatures.

Having thus disclosed the various components of the solution, an exampleof how the solution is prepared will now be disclosed. However, thisinvention is not intended to be limited by the order or method in whichthe components are mixed together, unless the components cannot be mixedin that order, or by that method, to provide the solution that isdisclosed herein. Additionally, this invention is not intended to belimited by the chemicals used in the examples below.

In its broadest aspect, the solution of this invention can be made bymixing together the acid component and water, and then by adding to thismixture, the metal, in either a solid or liquid form. The metal/acidmixture thus formed is then mixed together with the amine component, toform the solution of this invention.

As an example, the inventors first mix the metal and acid together. Onemethod of preparing this metal/acid mixture is to mix 45 gallons ofwater with 5 gallons of sulphuric acid that is in the form of achelating agent, for example, Stabitrol™ obtained from Cheltec. Two50-pound bags of the solid copper sulphate pentahydrate obtained, forexample, from HCI Canada Inc., in the form of a solid that is 25.2percent copper, may then be added while mixing. This metal/acid mixturewill therefore comprise about 5 percent by weight copper and about 2percent by volume sulphuric acid in the form of a chelating agent.Alternatively, it comprises about 5 percent by weight copper and 5percent by volume of a derivative of a sulphur-based acidic compound. Ifzinc is the metal component of the solution, solid zinc sulphatemonohydrate obtained, for example, from Tetra Micronutrients, in theform of a solid that is 35.5 to 38 percent zinc, is added with mixing,to a final concentration of about 6 to 9 percent zinc by weight.

A metal/acid mixture useful in making the solution of this invention canalso be obtained from Cheltec Inc., as a product known as Odorabate™,which is a solution of 2 percent sulphuric acid in the form of achelating agent and 5 percent copper. Alternatively, a product known asCT-307™ may be obtained from Cheltec, Inc. in the form of a 9 percentzinc chelate. Either of these solutions from Cheltec Inc. can be used asthe metal/acid mixture herein.

The metal/acid mixture is then mixed with any additional water, asrequired to bring the solution to its final volume. Additional watershould not be added to the amine component. The metal/acid mixture isthen quickly added to the amine component, with mixing to preventprecipitation of the metal. When the metal is zinc, mixing must beparticularly vigorous, as zinc will otherwise precipitate out of thesolution. The inventors have noticed that the temperature of thesolution, upon mixing of the metal/acid mixture with the amine willrise, in some instances up to 120° F., indicating that some type ofchemical reaction has occurred. The solution is then allowed to coolbefore use in the methods of this invention. It should be noted that, ifthe amine component is present at about 10 percent by volume of thefinal volume of the solution, or less, the temperature change to 120° F.does not occur, indicating that the presumed chemical reaction betweenthe components from which the solution is made, does not occur.

If the amine component will be less than about 37% by volume of thesolution, water should not be added to the amine component before themetaVacid mixture is mixed with the amine. Rather, additional watershould be added to the metal/acid mixture first, and then this solutionis added to the amine component. More vigorous blending is required inthis embodiment of the solution, to ensure that the solution is stable.

One embodiment of the solution comprises about 30 percent by volume ofthe 5 percent (w/v) copper and 2 percent sulphuric acid in the form of achelating agent mixture disclosed above; about 16 percent by volumemonoethanolamine; about 40 percent by volume ethylene glycol, and aboutan additional 14 percent by volume water.

One embodiment of the solution comprises about 30 percent by volume ofthe 5 percent (w/v) copper and 5 percent (v/v) derivative of asulphur-based acidic compound mixture disclosed above; about 16 percentby volume monoethanolamine; about 40 percent by volume ethylene glycol,and about an additional 14 percent by volume water.

In another embodiment, the solution comprises about 30 percent by volumeof the 5 percent (w/v) copper and 2 percent (v/v) sulphuric acid in theform of a chelating agent mixture disclosed above; about 30 percent byvolume monoethanolamine, and about 40 percent by volume methanol.

In another embodiment, the solution comprises about 30 percent by volumeof the 5 percent (w/v) copper and 5 percent (v/v) derivative of asulphur-based acidic compound mixture disclosed above; about 30 percentby volume monoethanolamine, and about 40 percent by volume methanol.

In another embodiment, the solution comprises about 30 percent by volumeof the 9 percent (w/v) zinc and 2 percent (v/v) sulphuric acid in theform of a chelating agent mixture disclosed above; about 30 percent byvolume monoethanolamine, and about 40 percent by volume ethylene glycol.

In another embodiment, the solution comprises about 30 percent by volumeof the 9 percent (w/v) zinc and 5 percent (v/v) derivative of asulphur-based acidic compound mixture disclosed above; about 30 percentby volume monoethanolamine, and about 40 percent by volume ethyleneglycol.

In another embodiment the solution comprises about 25 percent by volumeof the 5 percent (w/v) copper and 2 percent (v/v) sulphuric acid in theform of a chelating agent mixture disclosed above; about 16.7 percent byvolume monoethanolamine, about 41.6 percent by volume ethylene glycoland about an additional 16.7 percent by volume water.

In another embodiment the solution comprises about 25 percent by volumeof the 5 percent (w/v) copper and 5 percent (v/v) derivative of asulphur-based acidic compound mixture disclosed above, about 16.7percent by volume monoethanolamine, about 41.6 percent by volumeethylene glycol and about an additional 16.7 percent by volume water.

In another embodiment the solution comprises about 50 percent by volumeof the 5 percent (w/v) copper and 2 percent (v/v) sulphuric acid in theform of a chelating agent mixture disclosed above and about 50 percentby volume monoethanolamine.

In another embodiment the solution comprises about 50 percent by volumeof the 5 percent (w/v) copper and 5 percent (v/v) derivative of asulphur-based acidic compound mixture disclosed above, and about 50percent by volume monoethanolamine.

In another embodiment the solution comprises about 50 percent by volumeof the 6 percent (w/v) zinc and 2 percent (v/v) sulphuric acid in theform of a chelating agent mixture disclosed above and about 50 percentby volume monoethanolamine.

In another embodiment the solution comprises about 50 percent by volumeof the 6 percent (w/v) zinc and 5 percent (v/v) derivative of asulphur-based acidic compound mixture disclosed above, and about 50percent by volume monoethanolamine.

In another embodiment the solution comprises about 50 percent by volumeof the 9 percent (w/v) zinc and 2 percent (v/v) sulphuric acid in theform of a chelating agent mixture disclosed above and about 50 percentby volume monoethanolamine.

In another embodiment the solution comprises about 50 percent by volumeof the 9 percent. (w/v) zinc and 5 percent (v/v) derivative of asulphur-based acidic compound mixture disclosed above, and about 50percent by volume monoethanolamine.

In another embodiment the solution comprises about 50 percent by volumeof the 5 percent (w/v) copper and 2 percent (v/v) sulphuric acid in theform of a chelating agent mixture disclosed above, 25 percent by volumemonoethanolamine and an additional 25 percent by volume water.

In another embodiment the solution comprises about 50 percent by volumeof the 5 percent (w/v) copper and 5 percent (v/v) derivative of asulphur-based acidic compound mixture disclosed above, 25 percent byvolume monoethanolamine and an additional 25 percent by volume water.

In another embodiment the solution comprises about 50 percent by volumeof the 6 percent (w/v) zinc and 2 percent (v/v) sulphuric acid in theform of a chelating agent mixture disclosed above 25 percent by volumemonoethanolamine and an additional 25 percent by volume water.

In another embodiment the solution comprises about 50 percent by volumeof the 6 percent (w/v) zinc and 5 percent (v/v) derivative of asulphur-based acidic compound mixture disclosed above, 25 percent byvolume monoethanolamine and an additional 25 percent by volume water.

The pH of the resultant solution will generally be between 8 and 12, butcan be adjusted to almost any pH. The inventors have determined that thesolution is very efficient at removing hydrogen sulphide when the pH isadjusted to be above 8 and most efficient in the 10 to 11 range. Withoutbeing limited to a theory, this is likely the result of the fact thathydrogen sulphide is significantly more soluble at pH 8 than it is atacidic pHs.

Having thus disclosed the solution of this invention and how it isprepared, the methods for using the solution will now be disclosed. Inits broadest terms, one method of this invention is to prepare thesolution as described, and then to bring the solution into contact witha fluid that contains hydrogen sulphide. The fluid may be a gas or aliquid. As used herein, “gas” means a form of matter that has no fixedvolume and will conform in volume to the space available, and isintended to include mixtures of gases, such as air. For example, the gascan be natural gas that contains hydrogen sulphide, it can be air thatcontains hydrogen sulphide, and which is emitted from wastewater or fromagricultural operations, RV holding tanks, or portable toilets, forexample. The solution will, upon contact with the hydrogensulphide-containing gas or air, remove all or a significant portion of,the hydrogen sulphide. Without being limited to a theory, the hydrogensulphide reacts with the copper, zinc or iron in the solution to formcupric, zinc or iron sulphide, respectively, which are insolublemolecules that precipitate out of the solution.

Alternatively or in addition to hydrogen sulphide, a gas that is used inthe methods of this invention may comprise other sulphur compounds. Forexample, the gas may comprise mercaptans such as methyl mercaptan, ethylmercaptan, n-propyl mercaptan and/or iso-butyl mercaptan. Alternatively,or in addition, the gas may comprise carbonyl sulphide. The solutionwill, upon contact with a gas comprising one or more of these sulphurcompounds, remove all or a significant portion of these other sulphurcompounds from the gas.

Alternatively or in addition, a gas that is used in the methods of thisinvention may comprise carbon dioxide. The solution of this inventionwill, upon contact with a gas comprising carbon dioxide, remove asignificant portion of the carbon dioxide from the gas. This removalappears to be most efficient at cold temperatures. The solution alsoappears to have some effect on nitrogen levels.

FIG. 1A shows one embodiment of the method of this invention in which agas comprising one or more compounds that are to be removed from the gasis bubbled through a solution of the invention. Examples of thecompounds that are to be removed from the gas include, hydrogensulphide, mercaptans, such as methyl mercaptan, ethyl mercaptan,n-propyl mercaptan and iso-butyl mercaptan, carbonyl sulphide, andcarbon dioxide. As seen in FIG. 1, solution 10 is placed into acontainer 12 that has an entrance opening 14 and an exit opening 16.Entrance opening is fitted with a device 15, such as a one-way valve,that will prevent solution 10 from running out of container 12. The gas18 enters container 12 through entrance opening 14 and passes throughsolution 10 by rising upwards because of its low density. Gas 18 exitscontainer 12 through exit opening 16.

As is apparent, the gas 18 moves through solution 10 as a series ofbubbles, which increases the surface area of the interaction betweensolution 10 and gas 18, and causes turbulence in solution 10, both ofwhich increase the efficiency of removal of the desired compounds fromgas 18.

FIG. 1B shows another embodiment of the method of this invention, inwhich solution 10 is passed through tortuous paths 20 in container 12,rather than simply being introduced into container 12 as a volume ofliquid. In the method of this embodiment, container 12 again comprisesentrance opening 14 and exit opening 16 through which a gas 18 willenter into and exit from container 12. These openings are positionedsuch that gas 18 must pass through the tortuous paths 20 after enteringand before exiting container 12. Additionally, container 12 comprises anopening 15 and an exit 17, through which solution 10 will enter and exitcontainer 12, which are positioned such that solution 10 must passthrough the tortuous paths 20 after entering and before exitingcontainer 12. As is apparent, the tortuous paths both increase contactof solution 10 with gas 18, and also provide turbulence to solution 10,both of which increase the efficiency of removal of the compounds fromgas 18.

FIG. 1B demonstrates an embodiment of this invention in which thetortuous path is created by introducing a plurality of objects 22, suchas small circular balls or “ration rings”, into container 12. In oneembodiment, these balls are approximately the size of a golf ball.However, balls of different or varying sizes, objects that are notround, but oval or discoid, objects that have rounded and flat edges, orobjects with flat edges may be used. Any objects that would function tocause solution 10 and gas 18 to travel around and between them, areintended to be included herein. These objects function to increase thesurface area of interaction between the solution 10 and gas 18.

In this embodiment of the method of, this invention, solution 10 isintroduced into container 12, in such a way that maximizes its contactwith the surface of the objects 22. As demonstrated in FIG. 1B, this maybe accomplished by spraying solution 10 over the top surface of theobjects, whereafter it will trickle down through the various tortuouspaths.

Container 12 may be adapted to collect the gas that exits through exitopening 16, for example to collect natural gas. Alternatively, if thegas 18 is not to be collected, such as after the compounds have beenremoved from gases emitting from wastewater or from water used inagricultural operations, the gas would be released directly into theatmosphere, presuming it is otherwise clean.

In yet another embodiment of the method of this invention, the solutionis mixed with water and misted into a vessel containing gaseous sulphurcompounds and carbon dioxide.

In yet another embodiment of this method that is used with steaminjection, the solution is injected into steam to react with any sulphurcompounds and carbon dioxide that might be in the atmosphere as well asreact with any liquids that might be within the tank.

Another embodiment of the method of this invention is to prepare thesolution as described, and then to mix the solution with another liquidthat contains one or more of hydrogen sulphide, mercaptans, such asmethyl mercaptan, ethyl mercaptan, n-propyl mercaptan and iso-butylmercaptan, carbonyl sulphide or carbon dioxide. When the solution andthe liquid are mixed, and without being limited to a theory, the sulphurcompounds in the liquid will react with the metal in the solution toform a metal sulphide, an insoluble molecule that precipitates out ofthe solution. This precipitate can be removed from the mixture, forexample by filtration or centrifugation. Alternatively, removal of theprecipitate may not be necessary, for instance in a situation where theliquid is a drilling fluid used in oil and gas well drilling.

In particular, the solution may be mixed with liquid hydrocarbons inorder to react with naturally occurring sulphur compounds, such asmercaptans. This would be done under temperature and pressure.

In yet another embodiment, drilling mud is mixed with the solution ofthis invention, in order to remove therefrom a number of compoundsincluding, hydrogen sulphide, carbonyl sulphide, mercaptans such asmethyl mercaptan, ethyl mercaptan, n-propyl mercaptan and/or iso-butylmercaptan, or carbon dioxide.

As disclosed in Example 4, the solution of this invention is notcorrosive. The fact that it is not corrosive is of benefit in thehandling, use and transport of the solution, as compared to othersolutions that may be used for similar purposes and which are corrosive.As well, the solution of this invention is not flammable, it can bediluted in water, and it has a mild odor.

As will be apparent to those skilled in the art, various modifications,adaptations and variations of the preceding and foregoing specificdisclosure can be made without departing from the scope of the inventionclaimed herein. The following examples are intended only to illustrateand describe the invention rather than limit the claims that follow.

EXAMPLES Example #1

A mixture of 10% Stabitrol™ and 90% water has a freezing point of around0° C. and a pH of below one. Amine alone has a freezing point of around0° C. and a pH of between 12-13. The inventors have shown that when 5%Stabitrol™, 45% water and 50% amine are mixed, the solution heats up toabout 120° F. during the mixing process, and the freezing point of thefinal solution is below −51° C. and has a pH of between 10-11. Normallywhen these chemicals are used independently of one another in coldweather an anti-freeze agent would have to be added. This new mixtureeliminates the need for an anti-freeze agent, when using this solutionin cold weather.

The percentage of each chemical in this mixture can be varied a greatdeal, and the resultant mixture will still remain stable, meaning thatthe metal ion will remain in solution. The percentage of any particularchemical will be based on the application for the mixture, and the pH atwhich it is required to be effective.

The inventors have made different embodiments of the solution of thisinvention, in order to determine the freezing point of these variousembodiments. A copper/acid mixture, comprising 5% by weight copper andabout 2% by volume sulphuric acid in the form of a chelating agent wasprepared as described in the detailed description. Additionally an acidsolution without copper was prepared, using Stabitrol™. Various amountsof these solutions were then mixed with monoethanolamine, and thefreezing point of the solution was measured. The results are provided inTable 1.

TABLE 1 Monoethanolamine (volume %) Freezing Point Copper/Acid Mixture(volume %) 25 75 below −51° C. 50 50 below −51° C. 75 25 −18° C. 83.3416.66 −15° C. Acid Solution (volume %) 50 50 below −51° C.

Additionally, used solution from a test run was subjected to a freezingpoint analysis, and it was found to freeze at below −51° C.

These results indicate that a solution of acid and amine, or a mixtureof acid, amine and metal will have a much lower freezing point than eachof the individual liquid components of that solution

Example 2

A series of initial field trials using a mixture of Stabitrol™, waterand copper to remove H₂S from gas, were performed. The results of theseinitial tests were poor, and the inventors believed this to be becausethe pH was too low, as the pH of this mixture was about one. Theinventors hypothesized that the pH of the mixture needed to be at 8 to10, as the H₂S is much more soluble in a high pH, and therefore there isa much longer contact time between the copper and the H₂S.

As the mixture being used for H₂S scavenging should preferably be aliquid in a colder environment, the inventors added an anti-freeze tothe Stabitrol™, water and copper mixture, as at the time, they believedthe mixture would freeze at around 0° C. When an anti-freeze was added,the results were a little better. However, the inventors found that itwas not the anti-freeze that was causing the better results, but ratherit was the 2% amine used in the anti-freeze as a corrosion inhibitor,that was making the difference. The solution remained stable with 2%amine mixed into it. Hypothesizing that more amine would be even betterat removing H₂S, 5% amine was added to the solution. However, when thiswas done the product became unstable, in that the copper precipitatedout of the solution. When 10% amine was added, the mixture heated up andthe solution remained stable thereafter. Another series of field trialsusing new formulas was started.

The next series of tests were done using this Stabitrol™, water, copper,amine and glycol/methanol mixture (as anti-freeze agents). Severaldifferent formulas were tested to determine which ones would work thebest. There was a wide range of formulas that could be used, and theresults were much better than the previous field trials that had beendone. The pH of the mixtures generated was between 8 and 11.

The inventors mixed Stabitrol™, water, copper and amine together. Uponmixing these ingredients together the solution heated up to 120° F.,indicating that a chemical reaction was occurring. The mixture had afreezing point of below −51° C., therefore by using this mixture therewas no need for an anti-freeze to be added. A field trial was run to seeif H₂S removal was still effective, and the results were very good.

Continued field trials indicated that there are a wide range of formulasthat will yield solutions that are effective as H₂S scavengers. The pHis approximately 10.4 in a 50% (10% (v/v) Stabitrol™, water, 5% (w/v)copper) and 50% amine mixture. It appears that the formula can be variedin many ways, and the final formulations used will depend on theapplication and climate.

Test #1

20 liters of a solution of: zinc-chelate, (6 liters); monoethanolamine(3.3 liters), glycol (8 liters) and water (2.7 liters), was prepared. 19liters of this solution was used, but as 2 liters of this was left inthe fill hose, only 5.368 liters of the zinc-chelate solution was intower. The gas had a H₂S content of 8500 ppm. The flooded tower was notreverse circulating. The results are in Table 2. Approximately 5.3 m³ ofgas having 8500 ppm H₂S, was cleaned with about 5.3 liters of the zincchelate. These were the best results to date, and considering that thetest was done at flow rates of 6 m³ per hour, which is high for thistower, zinc seemed to provide results comparable to those obtained withcopper.

TABLE 2 Time of Meter Reading [H₂S] Total m³ through Day (m³) (ppm)Tower  9:30 103.5 0 0  9:45 105.2 0 1.5 10:00 106.7 0 3.0 10:15 108.2 04.6 10:22 109.0 8500 5.5

Test #2

20 liters of a solution of: Odorabate™ (6 liters), monoethanolamine (6liters) and methanol (8 liters), was prepared. About 19 liters ofproduct was tested. The gas had H₂S content of 8500 ppm. The floodedtower was packed with ration rings and was not reverse circulated. Theresults are in Table 3. About 6.75 m³ of gas having 8500 ppm H₂S, wascleaned.

TABLE 3 Time of Meter Reading [H₂S] Total m³ through Day (m³) (ppm)Tower  9:21 132.63 0 0  9:30 132.94 0 0.61  9:45 133.62 0 0.99 10:00134.2 0 1.57 10:15 134.78 0 2.15 10:30 135.3 0 2.67 10:45 135.83 0 3.211:00 136.38 0 3.75 11:15 136.9 34 4.27 11:21 137.15 54 4.54 11:30137.45 88 4.82 11:40 137.82 134 5.19 11:45 138.02 169 5.39 11:50 138.2199 5.59 11:55 138.4 244 5.79 12:00 138.54 270 5.93 12:05 138.75 3416.12 12:10 138.93 372 6.3 12:15 139.05 421 6.42 12:20 139.23 750 6.612:30 139.75 4200 7.12 12:40 140.08 6800 7.45 12:50 140.6 8500 7.97

Test #3

20 liters of a solution of monoethanolamine (3.3 liters), ethyleneglycol (8 liters) and water (8.7 liters) was prepared. 19 liters ofsolution was tested. The gas had H₂S content of 8500 ppm. The tower wasflooded, the column was packed with ration rings, and it was not reversecirculating. No Stabitrol™ or Odorabate™, or acid/metal solution wasused in this test. The results are shown in Table 4. For the first time,vapors were seen coming off of the gas sampling line. After tabulatingthe total volume of gas, it was calculated that 3.95 m³ of gas wascleaned.

TABLE 4 Time Meter Reading [H₂S] Total m³ through of Day (m³) (ppm)Tower 1:00 140.35 3 0 1:15 140.50 5 0.15 1:30 141.52 24 1.17 1:45 142.1054 1.85 2:00 142.6 98 2.25 2:15 143.24 202 2.89 2:30 143.85 376 3.502:45 144.36 2000 4.0 3:00 144.92 6500 4.6 3:15 145.48 8500 5.13

Test #4

18 liters of a 50:50 Odorabate™/monoethanolamine solution was prepared.No glycol or methanol was used. The outside temperature was −4° C.;there was 24 psi of pressure on the gas system, and the gas had a H₂Scontent of 8500 ppm. The tower was flooded and the column was packedwith ration rings. About 18 liters of solution was tested. The resultsare shown in Table 5. About 11.38 m³ of gas with an H₂S content of 8500ppm was cleaned. Therefore, this blend can clean 1.26 m³ of gascomprising 8500 ppm H₂S. With several of the tests that have been doneto date, just before breakthrough of H₂S, the gas flow increasedslightly. Perhaps if this did not happen, the total volume of gascleaned would have been extended for a longer period of time.

TABLE 5 Meter Reading [H₂S] Total m³ through Time (m³) (ppm) Tower 3:12145.04 0 0 3:30 145.67 0 0.63 4:00 146.7 0 1.66 4:30 148.0 0 3.00 5:00148.7 0 3.66 5:30 149.62 0 (-8° C.) 4.58 6:00 150.84 0 5.8 6:30 152.04 07.0 7:00 153.22 15 8.18 7:15 153.72 66 8.68 7:30 154.19 99 9.15 7:45154.8 345 9.76 8:00 155.34 800 10.3 8:15 156.0 2000 11.00 8:30 156.53000 11.46 8:45 157.0 5000 12.05 9:00 157.48 8500 12.44

Example 3

Each test was conducted in a test vessel that had a test tower which wasfour-inches in diameter and 10 feet tall, and included a sparger bar¾-inches in diameter and about 4 inches long with eight holes, 3/32inches in diameter, drilled at a 45 degree angle alternately to eachside of center. A flow meter was used to measure gas flow and there wasa flow line to the flare stack. The gas used in these tests was sourgas. Pressure, temperature, and the H₂S content of the gas variedbetween tests.

The concentration of the H₂S in the gas used varied because severaldifferent oil and gas wells were fed into the test complex. If theoperator had problems and shut in some wells, the amount of H₂S in thesample would change, as H₂S content differed from well to well.

When there was pressure on the tower, actual flow rates wereconsiderably higher because the gas was compressed. There are setdifferentials for pressure. The earlier of these tests did not recordany pressure, because it was cold outside and the line to flare wasclear plastic, so any blow by could be observed. In the winter, theplastic hose maintained its round structure, and the flow was notrestricted. The summary data reported at the end of this sectionincludes a 3 psi pressure factor that was included because of the heightof the fluid in the tower.

The later tests were done at a warmer temperature and the flare linecollapsed because it was made of plastic, causing back pressure on thesystem. A pressure of 5 to 10 psi caused considerable differences inactual flow rates. The summary data reported at the end allows for thesepressure differences. Pressure in working vessels will keep gas bubblessmaller, allowing for better contact with liquids it is bubblingthrough.

The results of tests of various solutions are outlined in the tablesbelow. The object of these tests was to determine how long each solutionwas able to maintain an “H₂S Out” (see below) of 0 ppm of H₂S. The“breakthrough point” is the point at which “H₂S Out” rises above 0 ppmof H₂S. “Time” is the time of day when the measurements were recorded.“Flow” is the flow rate of natural gas from an on-site well. “H₂S In” isthe concentration of hydrogen sulphide in the gas that is entering thetower, and “H₂S Out” is the concentration of hydrogen sulphide in thegas that exits the solution in the tower. “Colour” is the colour of thesolution near the middle of the solution when it is in the tower. “Fluidlevel” is the level that the fluid reaches in the tower while the gas isflowing into the tower. All tests used a volume of 10 liters ofsolution, with the exception of the test shown in Table 12, which used 9liters of solution.

Test #1

A solution of approximately 30% (w/v) of ammonium hydroxide (StrikeOilfield Services; Univar) was tested using the above methods. Theoutside temperature was −4° C., testing was done at atmosphericpressure. The flow meter was not working during this test. The resultsare shown in Table 6.

TABLE 6 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in) 12:45  1:47 1800 0 clear 14.3 40 12:47  1:47 ″ 0 clear 1:03 ″ ″ 0dark grey 80 1:15 ″ ″ 0 dark grey ″ 1:45 ″ ″ 1000 almost black, and someblue 10.5  31.5

Test #2

A solution of 5% (v/v) Stabitrol™; 2.5% (w/v) copper and 50% (v/v)monoethanolamine was tested. The outside temperature was −4° C. and nopressure was applied during the test. The results are shown in Table 7.The solution did not foam during the test. The byproduct of the reactionwas very thick, and the use of a sparger bar made this a very efficienttower. The byproduct was centrifuged and the result was approximately70-80% solids. These solids, when placed in a beaker of water, instantlybroke up and dispersed into water. No particles were over 4 microns.Byproduct adhered to the walls of the pipe during the use of thesolution, however the walls washed off clean when 7 liters of water waspoured into the top of the column. The flow meter was not working duringthis test.

TABLE 7 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in) 3:30 1:475 1500-1800 0 dark blue 10.8 45 3:31 ″ 97 3:45 1:475 ″ 0blue black 97 4:00 ″ ″ ″ ″ ″ 4:15 ″ ″ ″ black ″ 4:30 ″ ″ ″ ″ ″ 4:45 ″ ″″ ″ ″ 5:00 ″ ″ ″ ″ ″ 5:15 ″ ″ ″ black; can't see opaque 5:30 ″ ″ ″black; ″ opaque 5:45 ″ ″ ″ black; ″ opaque 6:00 ″ ″ ″ black; ″ opaque6:15 ″ ″ ″ black; ″ opaque 6:30 ″ ″ 12  black; ″ opaque 6:45 ″ ″ 100  ″

Test #3

A solution of 5% (v/v) Stabitrol™, 3.5% (w/v) zinc and 50% (v/v)monoethanolamine was tested. The outside temperature was −6° C. and nopressure was applied during the test. The results are shown in Table 8.The solution did not foam during the test. The byproduct of the reactiondid not adhere to the walls of the tower, as did the byproduct of thecopper solution used in the example above. By 3:45 the byproduct wasmore grey than black and was getting more viscous. By 4:40, it was verythick and starting to adhere to the walls. The flow meter was notworking during this test.

TABLE 8 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in) 11:30  1:47 1800  0 black 10.1  46 11:45  ″ ″ ″ ″ ″ 91 12:00  ″ ″ ″″ ″ 92 12:15  ″ ″ ″ ″ ″ 92 12:30  ″ ″ ″ ″ ~94  12:45  ″ ″ ″ ″ ″ ″ 1:00 ″″ ″ ″ ″ ″ 1:15 ″ ″ ″ ″ ″ ″ 1:30 ″ ″ ″ ″ ″ ″ 1:45 ″ ″ ″ ″ ″ ″ 2:00 ″ ″ ″″ ″ ″ 2:15 ″ ″ ″ ″ ″ ″ 2:30 ″ ″ ″ ″ ″ ″ 2:45 ″ ″ ″ ″ ″ ″ 3:00 ″ ″ ″ ″ ″″ 3:15 ″ ″ ″ black ″ 91-94 3:30 ″ ″ ″ ″ ″ ″ 3:45 ″ ″ ″ grey black ″ ″4:00 ″ ″ ″ grey ″ ″ 4:15 ″ ″ ″ very grey ″ ″ 4:30 ″ ″ 10 ″ ″ ″ 4:40 ″ ″35 ″ ″ ″ 5:00 ″ ″ 120  ″ 8.2 ″ 41

Test #4

A solution of 5% (v/v) Stabitrol™ and 2.5% (w/v) copper was tested. Theoutside temperature was 0° C. Results are shown in Table 9. This productturned black when filling. Five minutes after starting the experiment,defoamer had to be added. 17 ml of defoamer in 0.5 L H₂O was added. 25minutes after the start of the test 6-8″ of dark foam was visible on thetop of the pipe and by 35 minutes after the start of the test, the fluidreached the top of the tower and there was continued foaming with carryover. The test was stopped because of carry over. While the column wasbeing drained, a sample of the spent fluid was collected, and itimmediately started to separate with the clean fluid being blue. Thissolution does not appear to be able to be used for bubbling gas throughto remove H₂S from the gas.

TABLE 9 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in) 12:05 1500-1800 black 48 12:10 ″ 20 black 9 feet 12:30 ″ 10 black45 12:40 ″ 10 black 1.2 top of tower

Test #5

A caustic soda solution (3% (w/v), available from Univar or StrikeOilfield Services) was tested. The outside temperature was 0° C. Theresults are shown in Table 10. This solution did not foam. Due to animproperly operating flow meter, it is assumed that there was a flow of3.1 to 3.2 m³ every 15 minutes.

TABLE 10 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in) 1:32 1800 turned black 11.2 474 1:34 ″ 0 ″ 97 1:37 ″ 0 ″ 1:45 7.26″ 0 ″ 93 2:00 9.03 ″ 0 ″ 97 2:15 13.02 ″ 15 ″ 97 2:30 16.44 ″ 30 ″

Test #6

A solution of 10% (v/v) Stabitrol™ and 9% (w/v) zinc was tested. Theoutside temperature was 2° C. The results are shown in Table 11. Thesolution was a light tan color at the beginning of the test. The productdid not effectively remove hydrogen sulphide, as the flow rate was toofast and the product could not react with the H₂S.

TABLE 11 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in) 3:10 16.83 1800 turned black 1.3 48 3:11 97 3:15 17.90 ″ 1800 ″ 97

Test #7

A solution of 5% (v/v) Stabitrol™ and 50% (v/v) monoethanolamine wastested. The outside temperature was −3° C. The results are shown inTable 12. The solution was gold-colored at the beginning. Bubble actionwas visible when the control valve was fully opened. There was nofoaming. 30 minutes after the start of the test, the fluid was muchdarker. The byproduct of this reaction smelled like H₂S. Black flakeswere produced during the test and the composition of these flakes isunknown.

TABLE 12 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in) 10:30 19.06 2000 0 black 10.3 49 10:30 89 10:45 22.56 ″ 0 dark ″11:00 26.08 ″ 15 black 99 11:15 29.54 ″ 120 black 9.3 ″

Test #8

A solution of 100% (v/v) monoethanolamine was tested. The outsidetemperature was −2° C. The results are shown in Table 13. The solutionwas very difficult to drain out of the tower after this test wascompleted—although it was very runny, something held the flow back.

TABLE 13 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in) 11:55 29.97 2000 0 dark 12.5  55 33.28 ″ 5 dark 103 12:25 36.64 ″20 dark ″

Test #9

A solution of 5% (v/v) Stabitrol™, 3.5% (w/v) zinc and 50% (v/v)monoethanolamine was tested. The outside temperature was 0° C. Theresults are shown in Table 14. By 4:00 the solution was still very fluidand was not sticking to the walls of the tower. By 6:30 the fluid wasgetting stickier, by 7:10 it was sticking to pipe walls. The ending H₂Swas 2,000 ppm.

TABLE 14 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in) 1:07 37.61 2000  0 dark 10.1 47 1:07 86 1:15 40.10 ″ ″ dark ″ 1:3043.37 ″ ″ ″ ″ 1:45 47.06 ″ ″ ″ ″ 2:00 50.48 ″ ″ ″ ″ 2:07 52.05 ″ ″ ″ ″2:15 53082 ″ ″ ″ ″ 2:30 57.13 ″ ″ ″ ″ 2:45 60.47 ″ ″ ″ ″ 3:00 63.77 ″ ″″ ″ 3:15 67.07 ″ ″ ″ ″ 3:30 70.52 ″ ″ ″ ″ 3:45 73.94 ″ ″ ″ ″ 4:00 77.43″ ″ ″ ″ 4:15 80.86 2000  0 black 84 4:30 84.16 ″ ″ ″ ″ 4:45 87.36 ″ ″ ″5:00 91.06 ″ ″ ″ ″ 5:15 94.46 ″ ″ ″ ″ 5:30 97.83 ″ ″ ″ 80 5:45 101.36 ″″ ″ ″ 6:00 105.05 ″ ″ ″ ″ 6:15 108.62 ″ ″ ″ 82 6:30 112.17 ″ ″ ″ ″ 6:45115.73 ″ ″ ″ ″ 7:00 119.06 ″ 22 grey black ″ 7:10 121.38 ″ 60 ″ ″ 7:15122.33 ″ 80 ″ ″ 7:25 124.61 ″ 40 ″ ″ 7:30 125.77 ″ 60 ″ 7:45 129.15 ″120  ″

Test #10

A solution of 2.5% (v/v) Stabitrol™; 1.75% (w/v) zinc and 25% (v/v)monoethanolamine was tested. The outside temperature was 3° C. Theresults are shown in Table 15. At 4:15 the solution was very watery. Theend byproduct was very watery, but grey in colour. This may besignificant when it applies to a packed column or packed vessel usingreverse circulation, as the byproduct will circulate well, and will notbe difficult to clean out of a vessel. The test was shut down at 5 pm.

TABLE 15 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in) 12:55  130.53 2000 0 black 10.4 41 1:15 135.04 ″ ″ ″ 76 1:30 138.58″ ″ ″ ″ 1:45 141.52 ″ ″ ″ ″ 2:00 144.94 ″ ″ ″ ″ 2:15 148.45 ″ ″ ″ ″ 2:30151.92 ″ ″ black/grey ″ 2:45 154.84 ″ ″ ″ ″ 3:00 158.21 ″ ″ ″ ″ 3:15161.35 ″ ″ ″ ″ 3:30 164.28 ″ ″ ″ ″ 3:45 166.90 ″ ″ ″ ″ 4:00 169.70 ″ ″ ″″ 4:15 172.60 ″ 5 ″ 8.4 ″

Test #11

A solution of Sulfa Scrub HSW2001 (Baker Petrolite) was tested. Theoutside temperature was −4° C. The results are shown in Table 16. Thissolution did not foam and was still very fluid at 3:45. This solutioncontains 10% formaldehyde. After breakthrough occurs, the solutionappears to maintain relatively low emission of H₂S for some time, butthese emissions would be unacceptable in applications where 0 ppm mustbe maintained.

TABLE 16 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in) 11:50  173.21 400  0 black 42 12:15  179.23 ″ ″ ″ 76 12:30  182.77″ ″ ″ ″ 12:45  186.49 ″ ″ ″ ″ 1:00 190.10 ″ ″ ″ ″ 1:15 193.53 ″ ″ ″ ″1:30 196.90 ″ ″ ″ ″ 1:45 200.26 ″ ″ ″ ″ 2:00 203.52 ″ ″ ″ ″ 2:15 206.85″ ″ ″ ″ 2:30 209.90 ″ ″ ″ 66 2:45 213.08 ″ ″ ″ ″ 3:00 216.34 ″ ″ ″ ″3:15 219.60 ″ ″ ″ 61 3:30 222.77 ″ ″ ″ ″ 3:45 226.14 ″ ″ ″ ″ 4:00 229.49400  0 black 61 4:15 232.94 ″ ″ ″ ″ 4:30 236.23 ″ ″ ″ ″ 4:45 239.64 ″ ″″ ″ 5:00 243.22 ″ ″ ″ ″ 5:15 247.18 ″ ″ ″ ″ 5:30 250.70 ″ ″ ″ ″ 5:45254.36 ″ ″ ″ ″ 6:00 258.20 ″ ″ ″ ″ 6:15 261.46 ″  5 ″ ″ 6:30 264.80 ″ 10″ 60 6:45 267.86 ″ 10 ″ ″ 7:00 271.05 ″ 15 ″ ″ 7:15 274.35 ″ 20 ″ ″ 7:30277.42 ″ 15 ″ ″ 7:45 280.79 200 25 ″ 8.2 ″

Test #12

A solution of HSW0705F (Baker Petrolite) was tested. The outsidetemperature was −12° C. and 28 psi of pressure was applied to thesolution. The results are shown in Table 17. No foaming occurred. At theend of the test there was 200 ppm H₂S In. Gas volume dropped offdramatically.

TABLE 17 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in)  9:55 290.00 400  0 clear 10.4 42 10:15 294.44 ″ ″ ″ ″ 72 10:30297.84 ″ 10 fairly clear ″ ″ 10:45 300.23 ″ 15 ″ ″ 62 11:00 302.15 ″ ″ ″″ ″ 11:15 303.70 ″ 10 ″ ″ ″

Test #13

A solution of Sulfa Scrub HSW2001 (Baker Petrolite) was tested. Theoutside temperature was −12° C. The results are shown in Table 18. At2:00 the test had to be shut down in order to install another valve forsampling raw gas. The solution did not foam. At 4:30 the test was shutdown as there were problems with flow rate.

TABLE 18 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in) 11:45  303.95 2000 0 clear, dark 9.7 42 12:00  305.06 ″ ″ ″ ″ 5312:15  306.15 ″ ″ ″ ″ ″ 12:30  307.25 ″ ″ ″ ″ ″ 12:45  308.35 ″ ″ ″ ″ ″1:00 309.35 ″ ″ ″ ″ ″ 1:15 ″ ″ ″ ″ ″ 1:30 310.53 ″ ″ ″ ″ ″ 2:00 311.17 ″″ ″ ″ ″ ″ ″ ″ ″ ″ 2:30 311.72 <100 ppm ″ ″ ″ 3:00 312.79 ″ ″ ″ ″ ″ 3:30314.52  500 ppm ″ ″ ″ ″ 4:30 314.52

Test #14

A solution of Sulfa Scrub HSW2001 (Baker Petrolite) was tested. Theoutside temperature was −12° C. The results are shown in Table 19. Thisis a continuation of the test shown in Table 18, which had to be shutdown because the gas volume was only 11 m³ and the concentration of H₂Sdropped to less than 100 ppm. The fluid was left in the test tower andused in this test, which occurred two days later. When the test wasstopped at 5:20 there was an extraordinarily offensive smell emittingfrom it. As with the other test (test #11) of this solution, the resultsof which are shown in Table 16, after breakthrough the solution is ableto maintain 10 ppm to 20 ppm H₂S for a long period of time.

TABLE 19 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in) 10:55  314.76 400 0 clear, dark — 40 11:30  322.50 400 0 ″ — 7112:00  330.40 400 0 ″ — ″ 12:30  338.09 400 0 ″ — ″ 1:00 345.30 300 0 ″— 66 1:30 351.50 300 0 ″ — ″ 2:00 358.33 500 10  ″ — ″ 2:30 364.92 ″ ″ ″— ″ 3:00 371.60 350 ″ ″ — 62 3:30 377.64 ″ 15  ″ — ″ 4:00 384.80 ″ ″ ″ —″ 4:30 392.22 100-200 10  ″ — ″ 5:00 460.07 200 15  ″ — ″ 5:20 405.08200 20  ″ 8.1 35

Test #15

A solution of 30% (w/v) of ammonium hydroxide (Strike Oilfield Services,or, Univar) was tested using the above methods. The outside temperaturewas −7° C. The results are shown in Table 20. By 7:15 the solution wasvery dark.

TABLE 20 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in) 5:50 405.23 200  0 milky, clear 14.4  44 5:53 405.70 ″ ″ grey, dark″ 85 6:00 407.96 ″ ″ dark ″ 97 6:15 410.98 500 ″ ″ ″ 79 6:30 414.47 ″ ″″ ″ ″ 6:45 418.00 ″ ″ ″ ″ ″ 7:00 421.64 ″ 10 ″ ″ ″ 7:15 425.48 ″ 35 ″ ″″ 7:30 428.72 ″ 250  ″ 9.8 38

Test #16

A solution of 1% (v/v) sulphuric acid, 3.5% (w/v) zinc and 50% (v/v)monoethanolamine was tested. The outside temperature was 12° C. and nopressure was applied to the solution. The results are shown in Table 21.This solution did not foam. By 3:30 the fluid was so dark that it wasnot possible to see inside the pipe. By 5:30 it was very thick andblack.

TABLE 21 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in) 10:40  430.17  400  0 olive 43 11:00  434.01 ″ ″ ″ 76 11:30  440.30″ ″ ″ ″ 12:00  446.32 ″ ″ ″ ″ 12:30  451.74 ″ ″ ″ ″ 1:00 456.51 ″ ″ ″ ″1:30 460.45 ″ ″ ″ ″ 2:00 464.80 ″ ″ ″ ″ 2:30 467.60 ″ ″ ″ ″ 3:00 469.59″ ″ ″ ″ 3:30 471.06 1000 ″ ″ ″ 4:00 472.47 ″ ″ ″ ″ 4:30 473.56 ″ ″ ″ ″5:00 474.80 2000 10 dark ″ 5:15 475.44 ″ 60 ″ ″ 5:30 476.22 ″ 85 ″ 38

Test #17

A solution of 5% (v/v) Stabitrol™, 3.5% (w/v) zinc and 50% (v/v)monoethanolamine was tested. The outside temperature was 23° C. andthere was 5 psi of pressure in the tower. The results are shown in Table22. At 13:19 the flow was increased and pressure adjusted to 7 psi. Thesolution was still light and foamy at 13:45. The test was shut down at14:15 because of an H₂S monitor alarm. At 8:30 the next day the test wascontinued. The solution was so dark at that time that it wasn't possibleto see into the tube.

TABLE 22 Fluid Flow H₂S In H₂S Out Pressure Level Time (m³) (ppm) (ppm)Colour (psi) (in) 11:19 534.35 1500  0 dark brown 5 49 12:10 542.40 ″ ″″ 5 90 12:19 544.00 ″ ″ ″ 5 ″ 13:19 554.00 ″ ″ ″ 9 ″ 13:45 559.00 ″ ″light ″ 14:15 563.96 ″ ″ ″ ″  8:30 563.96 2000 ″ 5 ″  9:00 568.04 ″ ″brown 8 ″  9:30 572.26 ″ ″ ″ 8 ″ 10:00 576.83 ″ ″ ″ 7 ″ 10:15 578.40 ″ ″″ 7 ″ 10:30 581.05 ″ 20 ″ 7

Test #18

A solution of 5% (v/v) Stabitrol™, 4.5% (w/v) zinc and 50% (v/v)monoethanolamine was tested. The outside temperature was not recordedand there was no pressure in the column, The results are shown in Table23. There was some difficulty, in this test, with the H₂S readings. Thissolution did generate foam. Then end value for H₂S In was determined bygas tube RAE. (**)

TABLE 23 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in) 10:14 484.36 0 brown 46 10:30 486.66 0 ″ 75 11:05 0 ″ 11:14 493.600 ″ 11:37 0 ″ 84 12:14 0 light brown 96 12:15 502.13 0 ″ 13:12 510.00 0″ 96 14:15 517.07 0 opaque 15:17 523.87 0 16:15 526.51 1500 ** 14  69ambient @ 16:10

Test #19

A solution of 5% (v/v) Stabitrol™, 4.5% (w/v) zinc and 50% (v/v)diglycolamine was tested. The outside temperature was 24° C. and therewas 3 psi of pressure within the tower or column. The results are shownin Table 24. A layer of foam developed immediately, and at 11:15, 1liter of foam was pulled off the top of the liquid. By 11:30, foamingand carry over had stopped. A sample of gas was taken at 15:15, and H₂Sreading was at 0 ppm. At this time the solution was very fluid.

TABLE 24 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in) 11:10 581.07 1500+ 0 47 11:15 ″ 0 11:30 583.90 ″ 0 12:00 588.36 ″ 072 12:25 592.11 ″ 40 31

Test #20

A solution of 2.5% (v/v) Stabitrol™, 1.75% (w/v) zinc and 50% (v/v)monoethanolamine was tested. The outside temperature was 26° C. and 5psi of pressure existed within the tower. The results are shown in Table25. By 13:00 the byproduct began to stick to the sides of the tower.After the test was over, the solution drained very well as a very liquidfluid.

TABLE 25 Flow H₂S In H₂S Out Pressure Fluid Level Time (m³) (ppm) (ppm)Colour (psi) (in) 11:30 592.23 2000+ 0 brown 5 46 12:00 597.94 ″ 0 ″ 592 12:30 603.51 ″ 0 ″ 5 ″ 13:00 609.45 ″ 0 ″ 5 ″ 13:30 615.08 ″ 0 darker5 ″ 13:45 617.91 ″ 20 very dark 5 ″

Test #21

A solution of 3.5% (w/v) zinc and 25% (v/v) monoethanolamine was tested.The outside temperature was 26° C. and 5 psi of pressure was applied tothe solution. The results are shown in Table 26. The solution was fairlythick to begin with. At 3:00 the flow was cut, because the pressure wastoo high, after which the pressure was held at 5 psi.

TABLE 26 Flow H₂S In H₂S Out Pressure Fluid Level Time (m³) (ppm) (ppm)Colour (psi) (in) 2:15 617.92 2000+  0 brown 5 46 3:00 627.20 ″ ″ ″ 10102  3:15 629.96 ″ ″ ″ 5 ″ 3:45 635.90 ″ ″ ″ 5 97 4:15 641.02 ″ ″ ″ 5 924:45 647.21 ″ ″ ″ 5 ″ 5:15 653.28 ″ ″ ″ 5 97 5:45 659.00 ″ ″ ″ 5 ″ 6:15664.57 ″ ″ ″ 5 92 6:45 669.97 ″ 10 ″ 5

Test #22

A solution of 3.6% (w/v) zinc and 20% (v/v) monoethanolamine was tested.The outside temperature was 24° C. and 5 psi of pressure existed withinthe tower or column. The results are shown in Table 27. In this solutionthe zinc did not seem to be completely dissolved.

Sticking of byproduct to the sides of the vessel was observed beginningat 12:40. The fluid was thin and drained well from the tower after thetest was over.

TABLE 27 Fluid Flow H₂S In H₂S Out Pressure Level Time (m³) (ppm) (ppm)Colour (psi) (in) 11:20  670.00 2000  0 white 5 46 12:40  683.75 ″ ″yellow brown 5 92 1:20 691.90 ″ ″ ″ 5 ″ 2:20 704.58 ″ ″ ″ 5 ″ 2:50710.43 ″ ″ ″ 5 ″ 3:20 716.77 ″ ″ ″ 5 ″ 3:50 721.53 ″ ″ ″ 5 ″ 4:25 727.75″ 15 red grey 5 ″

Test #23

Nine liters of drilling mud was mixed with 300 ml of a solution of 5%Stabitrol™, 3.5% zinc and 50% monoethanolamine, and 700 ml of water. Theoutside temperature was 24° C. and no pressure was applied to thesolution. The results are shown in Table 28. Flow was low in this test.

TABLE 28 Flow H₂S In H₂S Out Fluid Level Time (m³) (ppm) (ppm) Colour pH(in) 3:30 727.75 2000+ 0 brown 46 3:45 728.07 ″ ″ ″ 72 4:00 728.30 ″ 4 ″″ 4:15 728.85 ″ 500  ″ ″ 46

Test #24

A solution of 5% (v/v) Stabitrol™, 3.5% (w/v) zinc and 50% (v/v)monoethanolamine, was tested. In this test the monoethanolamine used wasnew, rather than recycled monoethanolamine. The outside temperature was20° C. and 5 psi of pressure was applied to the solution. The resultsare shown in Table 29. By 5:30, some byproduct began to stick to thesides of the vessel. There did not appear to be any noticeabledifference in the performance of this solution as compared to theprevious tests which used recycled monoethanolamine.

The spent fluid was left in the tower overnight. The next morning,approximately 3.5 liters of thick, grey spent product was added to 4liters of water, and sour gas flow was started. The meter reading (H₂SOut ) at 9:40 am with a flow of 775.67 m³, was 0 ppm. At 10:00 am with aflow of 777.47 m³ the reading was 15 ppm.

TABLE 29 Fluid Flow H₂S In H₂S Out Pressure Level Time (m³) (ppm) (ppm)Colour (psi) (in) 1:00 728.58 2000+ 0 dark 5 46 1:30 734.12 ″ 0 ″ 8 782:00 739.64 ″ 0 ″ 8 ″ 2:30 744.92 ″ 0 getting darker 10 ″ 3:00 749.79 ″0 ″ 8 ″ 3:30 754.52 ″ 0 ″ 3 ″ 4:00 579.70 ″ 0 ″ 5 ″ 4:30 764.92 ″ 0 ″ 5″ 5:00 770.09 ″ 0 ″ 9 ″ 5:30 775.09 ″ 100 looks darker 6 ″

Test #25

A solution of 5% (v/v) Stabitrol™, 3.5% (w/v) zinc and 37.5% (v/v)monoethanolamine, was tested. The outside temperature was 24° C. and 15psi of pressure was applied to the solution initially, but it was cutback to 5 psi. The results are shown in Table 30. By 2 pm the byproductwas starting to stick to the sides of the tower. The fluid was runny andeasy to drain from the tower after the test was over.

TABLE 30 Fluid Flow H₂S In H₂S Out Pressure Level Time (m³) (ppm) (ppm)Colour (psi) (in) 10:22 777.60 2000 0 olive 5 45 10:30 778.50 ″ 0 ″ 8 9211:00 781.00 ″ 0 ″ 9 98 11:30 783.44 ″ 0 ″ 10 82 12:00 787.41 ″ 0 ″ 10 ″12:30 790.88 ″ 0 ″ 10 ″  1:00 795.01 ″ 0 ″ 10 ″  1:30 799.32 ″ 0 ″ 10 ″ 2:00 804.62 ″ 0 ″ 10 ″  2:30 809.95 ″ 0 getting darker 10 ″  3:00814.85 ″ 60 dark 10 ″

Summary of Tests

Table 31 compares the results obtained with some of the solutions testedabove. These results are adjusted to an H₂S In of 2,000 ppm, a constantpressure and a constant flow of gas.

TABLE 31 Elapsed Time Before Sour Gas Scrubbed Solution TestedBreakthrough of H₂S Before Breakthrough (10 litres) (minutes) of H₂S(m³) 5% (v/v) Stabitrol ™; 353 81.45 3.5% (w/v) zinc; 50% (v/v)monoethanolamine Caustic Soda 39 8.25 Ammonia 18 4.10 Sulfa ScrubHSW2001 77 17.65 HSW0705F 7 2.04

When allowing for pressure differentials, H₂S variances and temperatureit is calculated that one liter of the 5% Stabitrol™, 3.5% zinc, 50%monoethanolamine solution disclosed herein will neutralize 8 to 9 cubicmeters of gas comprising H₂S at 2,000 ppm.

Diglycolamine (DGA) and MDEA were tested as alternative amines tomonoethanolamine, and although they work to some degree, neither of themwork as well as monoethanolamine for scavenging H₂S when used in thesolution of this invention.

Example 4

The corrosiveness of a 5% (v/v) Stabitrol™; 3.5% (w/v) zinc; 50% (v/v)monoethanolamine solution was tested using a wheel test method (NACEProcedure 1D182). The wheel test is the dynamic test performed byplacing the test fluid in a 1250 gm (150-cc) bomb bottle with a metalcoupon. The bottles are pressurized with sour gas if any sour test is tobe conducted with pressure in the system, and capping the bottle. Thebottle is then agitated for a period of time by securing it in thecircumference of a wheel and rotating it under pressure and temperature.The test is normally run for 2 to 3 weeks. After the test is completed,the tested coupons are removed from the bomb bottle and the pittingtendency is evaluated.

Two (2) pieces of 7.65 cm×1.125 cm×1.06 mm shim stock SAE 1020 steelwere used as a Coupon. This material can be readily observed for pittingtendency. A small hole of (5-mm in diameter) was drilled at one end ofthe coupons in order to place in the plastic cap. Coupons were cleanedwith benzene, wiped dry with a clean cloth and stored before weighing,and fingerprints were avoided by handling with clean latex gloves andforceps. The initial weight of the coupons was measured.

A stainless steel bomb bottle (150 cc capacity, high pressure andtemperature) was cleaned with toluene followed by isopropanol solution,blow dried with air and kept sealed before using. Then the coupon wasplaced in the plastic cap at the one end of the bomb. The bottle wasevacuated to avoid any air contamination. 100 cc of the solution beingtested was drawn into the test bomb bottle to fill approximately ⅔ ofits capacity. The capped bombs were placed on holders on the wheel androtated at 20° C. for 2 weeks.

After this time, the coupons were retrieved from the bomb bottle, rinsedwith xylene to remove solution film, wiped with steel wool pad to removeany corrosion by-product, and weighed. Then, the coupons were placed ina plastic bag and photographed.

This procedure may have many variables such as the effect of variouscontaminants in the solution, as well as air contamination. The weightloss for each coupon was determined and duplicates averaged and percentcorrosion is calculated as follows:% Corrosion=Weight loss (mg)/Weight before (mg)×100.

The results obtained for the 5% Stabitrol™; 3% zinc; 50%monoethanolamine solution are recorded in Table 32, and indicate thatthe solution is not corrosive.

TABLE 32 ID Initial Weight, (g) Final Weight (g) % Corrosion 1 5.7515.751 0.0 2 5.801 5.801 0.0 3 5.809 5.809 0.0 4 (Blank) 6.004 6.004 0.0Average Corrosion 0.0

Example 5

Samples of sour gas that were untreated or treated with a test solution,according to the methods disclosed in Example 3 above, were collected.These samples were subjected to gas analysis and trace sulphur analysisto determine which types of sulphur compounds were removed from thesample by treatment with the solution. The results of the tests areoutlined in tables below. For each sulphur compound tested, the methoddetection limit was 0.1 ppm. These results indicate that the solution ofthis invention consistently reduces carbonyl sulphide, methyl mercaptan,ethyl mercaptan and iso-butyl mercaptan. The solution also scavengescarbon dioxide in colder temperatures.

Gas samples collected before and after the use of a solution of 5%Stabitrol™ (v/v), 3.5% Zinc (w/v), and 50% (v/v) monoethanolamine wereanalysed. The results in Table 33 indicate that the solution testedreduces, in addition to H₂S, carbonyl sulphide, methyl mercaptan, ethylmercaptan, n-propyl mercaptan, iso-butyl mercaptan and carbon dioxide.These results indicate that the solution of this invention will removemany mercaptans from a gas.

TABLE 33 [ ] in [ ] in treated [ ] in treated gas before sample (ppm)sample (ppm) treatment [sampled [sampled Sulphur Compound (ppm) at11:30] at 12:00] hydrogen sulphide 1240 <0.1 <0.1 carbonyl sulphide 2.00.2 0.2 methyl mercaptan 3.1 0.1 0.3 ethyl mercaptan 5.5 0.4 1.4dimethyl <0.1 <0.1 0.1 disulphide carbon disulphide <0.1 <0.1 <0.1iso-propyl 2.1 1.1 4.7 mercaptan tert-butyl 0.1 0.2 0.2 mercaptann-propyl 0.9 0.1 0.3 mercaptan methyl ethyl <0.1 0.2 0.1 sulphidesec-butyl 1.3 0.4 1.0 mercaptan thiophene <0.1 <0.1 <0.1 iso-butyl 8.0<0.1 <0.1 mercaptan n-butyl <0.1 <0.1 <0.1 mercaptan tert-butyl methyl<0.1 <0.1 <0.1 sulphide dimethyl sulphide <0.1 <0.1 <0.1 diethylsulphide <0.1 <0.1 <0.1 unidentified 7.7 48.5 5.1 sulphur componentstotal organic 1270 52.8 13.4 sulphur Other Mole Frac. Mole Frac. MoleFrac. H₂ trace 0.0000 0.0000 He 0.0001 0.0001 0.0001 N₂ 0.0010 0.00360.0002 CO₂ 0.0420 0.0147 0.0209 H₂S 0.0012 0.0000 0.0000

Gas samples collected before and after the use of a solution of 5%Stabitrol™, 3.5% zinc and 37.5% monoethanolamine, were tested. Theresult of the on site test for this solution was reported in table 30,above. The sour gas sample was taken at 11:30 and treated gas sampleswere taken at 11:30 (column 1), 12:30 (column 2) and 14:30 (column 3).The samples were analysed for mole fraction of various compounds (seebottom of table), and some of the samples were subjected to a tracesulphur analysis. The results in Table 34 indicate that the solutiontested reduces, in addition to H₂S, carbonyl sulphide, methyl mercaptanand ethyl mercaptan. These results indicate that the solution of thisinvention will remove many mercaptans from a gas.

TABLE 34 [ ] in [ ] in sour gas treated gas sample (ppm) SulphurCompound (ppm) 1 2 3 hydrogen sulphide 1200 <0.1 0.8 carbonyl sulphide1.9 0.2 <0.1 methyl mercaptan 3.2 0.4 1.4 ethyl mercaptan 4.3 1.2 3.8dimethyl disulphide <0.1 <0.1 <0.1 carbon disulphide 0.2 <0.1 0.2iso-propyl mercaptan 3.2 2.5 5.5 tert-butyl mercaptan <0.1 0.1 0.1n-propyl mercaptan 0.8 0.4 0.9 methyl ethyl sulphide <0.1 <0.1 <0.1sec-butyl mercaptan 0.7 0.7 1.1 thiophene <0.1 <0.1 <0.1 iso-butylmercaptan <0.1 <0.1 <0.1 n-butyl mercaptan <0.1 <0.1 <0.1 tert-butylmethyl <0.1 <0.1 <0.1 sulphide dimethyl sulphide <0.1 <0.1 <0.1 diethylsulphide <0.1 <0.1 <0.1 unidentified sulphur <0.1 <0.1 <0.1 componentstotal organic sulphur 1210 5.5 13.8 Other Mole Frac. Mole Frac. MoleFrac. Mole Frac. H₂ 0.0000 trace trace 0.0000 He 0.0000 0.0001 0.00010.0001 N₂ 0.0046 0.0008 0.0040 0.0010 CO₂ 0.0365 0.0416 0.0385 0.0405H₂S 0.0012 0.0000 0.0000 Trace

Gas samples collected before and after the use of a solution of 5%Stabitrol™, 3.5% zinc and 50% monoethanolamine, were tested. The resultof the on site test for this solution was reported in Table 29, above.The sour gas sample was taken at 12:40 and treated gas samples weretaken at 14:00 (column 1), 15:00 (column 2), 16:00 (column 3) and 17:00(column 4). The samples were analysed for mole fraction of variouscompounds (see bottom of table), and some of the samples were subjectedto a trace sulphur analysis. The results in Table 35 indicate that thesolution tested reduces, in addition to H₂S, carbonyl sulphide, methylmercaptan and ethyl mercaptan. These results indicate that the solutionof this invention will remove many mercaptans from a gas.

TABLE 35 [ ] in [ ] in sour gas treated gas sample (ppm) SulphurCompound (ppm) 1 2 3 4 hydrogen sulphide 1240 <0.1 0.4 carbonyl sulphide0.9 <0.1 <0.1 methyl mercaptan 3.1 0.8 1.2 ethyl mercaptan 4.6 2.4 3.9dimethyl disulphide <0.1 <0.1 <0.1 carbon disulphide <0.1 0.8 0.4iso-propyl mercaptan 3.7 3.3 4.0 tert-butyl mercaptan <0.1 0.2 0.1n-propyl mercaptan 0.8 0.6 0.9 methyl ethyl sulphide <0.1 <0.1 <0.1sec-butyl mercaptan 1.3 1.0 0.9 thiophene <0.1 <0.1 <0.1 iso-butylmercaptan <0.1 <0.1 <0.1 n-butyl mercaptan <0.1 <0.1 <0.1 tert-butylmethyl <0.1 <0.1 <0.1 sulphide dimethyl sulphide <0.1 <0.1 <0.1 diethylsulphide <0.1 <0.1 <0.1 unidentified sulphur <0.1 <0.1 <0.1 componentstotal organic sulphur 1270 9.1 11.8 Other Mole Frac. Mole Frac. MoleFrac. Mole Frac. Mole Frac. H₂ trace 0.0000 0.0000 0.0000 Trace He trace0.0001 0.0000 0.0000 0.0001 N₂ 0.0042 0.0009 0.0036 0.0034 0.0015 CO₂0.0368 0.0317 0.0317 0.0370 0.0375 H₂S 0.0012 0.0000 0.0000 0.0000 Trace

Example 6

The inventors tested a variety of solutions to determine whether therewas a freezing point depression, and whether a heat reaction occurred,and the final pH. The freezing point and temperature reached duringreaction of the two components, for each solution, are outlined in

TABLE 36 Final volume % Final volume Heat reaction Freezing Stabitrol ™% MEA Temp (° F.) Point (° C.) pH 10 50 140 <-48 10.6 15 50 160 <-4810.1 7.5 37.5 140 -42 10.3 2.5 50 100 <-48 11.1 7.5 25 ND -23 10.4

Over a wide range of concentrations of Stabitrol™ and MEA, a depressionof freezing point, and a heat reaction were observed.

1. A solution for removing a sulphur compound or carbon dioxide from afluid, said solution comprising: (a) sulphuric acid, at between about0.1 to 4 percent by volume of the solution; (b) a metal, at betweenabout 0.05 to 10 percent by weight of the solution; (c) an amine, atbetween about 10 to 80 percent by volume of the solution; and (d) water.2. The solution of claim 1 wherein the sulphur compound is selected froma group consisting of: hydrogen sulphide, methyl mercaptan, ethylmercaptan, n-propyl mercaptan, iso-butyl mercaptan and carbonylsulphide.
 3. The solution of claim 1 wherein the metal is selected froma group consisting of: copper, zinc, iron, magnesium or manganese. 4.The solution of claim 1 wherein the metal is copper.
 5. The solution ofclaim 1 wherein the metal is zinc.
 6. The solution of claim 1 whereinthe amine is a primary amine.
 7. The solution of claim 1 wherein theamine is selected from a group consisting of: monoethanolamine,diglycolamine, methyldiethanolamine.
 8. The solution of claim 1 whereinthe amine is a mixture of amines.
 9. The solution of claim 1 wherein thesulphuric acid is present at between about 0.1 to 2 percent by volume ofthe solution.
 10. The solution of claim 9 wherein the metal is presentat between about 1 to 5 percent by weight of the solution.
 11. Thesolution of claim 10 wherein the amine is present at between about 25 to50 percent by volume of the solution.
 12. A method of removing a sulphurcompound or carbon dioxide from a fluid, comprising: (a) preparing asolution according to any one of the above claims, and (b) contactingthe fluid with the solution.
 13. The method of claim 12 wherein thesulphur compound is selected from a group consisting of: hydrogensulphide, methyl mercaptan, ethyl mercaptan, n-propyl mercaptan,iso-butyl mercaptan and carbonyl sulphide.
 14. The method of claim 12wherein the fluid is a gas.
 15. The method of claim 12 wherein the fluidis a liquid.
 16. The method of claim 14 wherein the gas is natural gas.17. The method of claim 14 wherein the gas is air.
 18. The method ofclaim 15 wherein the liquid comprises a liquid hydrocarbon.
 19. Themethod of claim 15 wherein the liquid is drilling mud.
 20. The method ofclaim 12 practiced at a temperature of between about 0° C. and −51° C.21. The method of claim 12 practiced at a temperature of between about−10° C. and 40° C.
 22. A method of removing a sulphur compound or carbondioxide from a gas, which method comprises: (a) preparing a solutionaccording to any one of the above claims, and (b) contacting the gaswith the solution, and characterized in that the method is performed ata temperature of between about 0° C. and −51° C.
 23. The method of claim22 performed at a temperature of between about −10° C. and 40° C. 24.The method of claim 22 performed at a temperature of between about −20°C. and 40° C.
 25. The method of claim 22 performed at a temperature ofbetween about −10° C. and −30° C.
 26. The solution of claim 1, whereinthe sulphuric acid is present at between about 1 to 4 percent by volumeof the solution.
 27. The solution of claim 1, wherein the sulphuric acidis present at about 2 percent by volume of the solution.
 28. Thesolution of claim 1, wherein the sulphuric acid is present at about 2.3percent by volume of the solution.
 29. The solution of claim 1, whereinthe solution has a pH of between about 8 and 12.